Granny square cropped sweater problem 😪

miney

Hi ?
Creating a granny square cropped sweater. I have over 3 videos now and patterns teaching me how to do it but I'm pretty confused because of the number of yarn I'm working with. I'm using milk cotton (the labeling is all in Chinese and I can't really read it well) the project I want to make has 10 granny square sewed together to make a large shrug (the wrist holes is half double crochet decrease to make it small) it granny square box has 10 rows. I'm using a 5mm hook. But it looks small somehow. When I tried using 6mm it looked too big. At this point im so confused. Im working with only 3 colors (white, dark purple, and black) and im also confused on what color pattern. Please what do you think im doing wrongly? Do I keep going with the 5m hook until its large enough or I should just stick to 6mm. And how do you think I should do the color pattern that can make it look pretty. Please any advice is much appreciated. Thank you in advance ??✨